Now that Hunter's Call has it's own emissary and gets reputation from bait crates, I think it should also be possible to hand in bait crates back to them (as long as they weren't bought at the current representative).
If there's design/technical reasons that only one company can accept these crates, I think lore could explain that prices for bait started to dip after HC started to sell them too, so the Merchant Alliance stopped offering the service (told by a line by one or two representatives of each company).
